Dirty fix for error '_object_has_no_attribute_'getSlave' in EtherCAT extension

traceback:
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 1433, in OnPouSelectedChanged
window.RefreshView()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 837, in RefreshView
self.RefreshProcessVariables()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 886, in RefreshProcessVariables
slaves = self.Controler.GetSlaves(**self.CurrentNodesFilter)
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/EthercatMaster.py", line 341, in GetSlaves
for slave in self.Config.getConfig().getSlave():
<type 'exceptions.AttributeError'>:_'lxml.etree._Element'_object_has_no_attribute_'getSlave'

Steps to reproduce problem:

- Add new EtherCAT master
- Add new EthercatNode to the master
- double click on


this is looks like dirty hack to fix strange problem with initial[0]
changing its type after returning from _init_ method to lxml.etree._Element
As a result all methods generated by class factory are lost.

For example, in function initMethod initial[0].__class__ points to
xmlclass.xmlclass.Config. After map(self.append, initial)
self.Config.__class__ is 'xmlclass.xmlclass.Config' as well.
But after returning from initMethod (_init) in CreateElement
self.Config.__class__ has changed to lxml.etree._Element.


I've noticed similar behavior if copy/deepcopy is used for any child
of etree.ElementBase. See simple example below.
[-------------------------------------------------------------]
#!/usr/bin/python

from __future__ import print_function
from lxml import etree
import copy

class DefaultElementClass(etree.ElementBase):
def getLocalTag(self):
return etree.QName(self.tag).localname


def printInformation(x):
print(x, x.__class__, "getLocalTag" in dir(x))


a = DefaultElementClass()
printInformation(a)

#
printInformation(copy.copy(a))
printInformation(copy.deepcopy(a))
[-------------------------------------------------------------]

Beremiz installation 
====================

Windows
-------
Download installer, install. 

Linux
-----
Pre-requisites::

    # Ubuntu/Debian :
    sudo apt-get install python-wxgtk2.8 pyro mercurial
    sudo apt-get install build-essential bison flex python-numpy python-nevow

Prepare::

    mkdir ~/Beremiz
    cd ~/Beremiz

Get Source Code::

    cd ~/Beremiz
    
    hg clone http://dev.automforge.net/beremiz
    hg clone http://dev.automforge.net/plcopeneditor
    hg clone http://dev.automforge.net/matiec

Build MatIEC compiler::

    cd ~/Beremiz/matiec
    ./configure
    make

Build CanFestival (optional):: 

    # Only needed for CANopen support. Please read CanFestival 
    # manual to choose CAN interface other than 'virtual'::

    cd ~/Beremiz
    hg clone http://dev.automforge.net/CanFestival-3
    
    cd ~/Beremiz/CanFestival-3
    ./configure --can=virtual
    make

Launch Beremiz::

    cd ~/Beremiz/beremiz
    python Beremiz.py